Ford 7.3L Power Stroke (1999-2003) :: Low Power - Fuel Pressure?
Aug 10, 2015
Low power on my 2003 7.3 F350. The truck runs fine but I can tell it is low on power (seat of the pants). I figured it to be fuel related so changed fuel filter and oil with no change. When that didn't work I installed a fuel guage and this what I found. Key on no start fuel pressure 45 psi. Start truck the pressure will get up to 61psi. Under a load it will drop down to the low 30s. I have dropped the tank mixing chamber screens clean and so was the tank. Changed fuel pump and now under a load it drops to the high 30s. Does this sound like the fuel pressure regulator is leaking by and causing low pressure under a load? Truck is stock besides superchips 1705 programer.
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I bought an Autometer 4763 gauge that didn't come with the correct fittings to plumb the sender into one of the extra ports on the back of the bowl. I went to the Ace hardware store right across the street and they didn't have anything (not surprised) and then Napa. They couldn't find a fitting to match either. He found that the plug threads are 7/16 20 tpi and the sender is 1/8" NPT. He suggested getting a 7/16 20tpi bolt, drilling it rifle-style, and then tapping it for a 1/8" NPT. The alternative, and what I ended up doing, was to use brass fittings to tee it off one of the supply lines to the heads. I ended up going that route but wanted to know if I should have looked harder for the right fitting.
Here's a pic of what I have now. I've test fit it, and it seems to work although I will need to insulate the hard lines because they rub due to the offset.
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Looking for pics of where/how they mounted their fuel pressure gauge? I'm getting ready to install one.
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Next mods are for the fuel rail cross over and the high pressure oil cross over. I see the unused ports will come in handy.
Fuel delivery? any specialty mods to run the fuel lines? I see it's a #4 ORB fitting. Anyone ever use a "T" or a splitter off the fuel bowl to have a quad line set up?
Saw the FRx from RiffRaff .... not sure how it eliminates air from the system 7.3L Diesel Fuel Rail Crossover? (FRx) 99-03 Powerstroke
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Last night when i left work I noticed my fuel pressure was running about 77 psi, it normally runs about 68psi. today I took my daughter to practice and it was around 83psi, on the way home it was up to 95psi, so I parked it and took another truck to work.
About a week and a half ago I lost fuel pressure going down the highway and the truck died, finally decided my pick-up foot must have come off and had my sister in law bring me some diesel and it has drove fine ever since. (it was right at a quarter tank).
I have the FRX from riffraff and am thinking some pieces of that foot have got into the fuel bowl and plugging up the return. Things to check? Could it be a problem with the fuel gauge or wiring, and how to test them. It is an autometer gauge from riffraff.
It will probably be a few weeks before I can do much more than clean out the fuel bowl. I don't have anywhere inside to work on it and it's been rain/sleet/freezing rain/snow for the last 10 days. I have most of the stuff to do the hutch mod and its next on the list but was hoping to put it off till spring.
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Just joined today, I have a 2003 550 7.3. New HPOP, 3 new injectors, new seals on others, new fuel pressure regulator, new fuel pump, sending unit mod to eliminate filters. 733 HPOP pressure, 65 fuel pressure at idle. Truck runs out of fuel pressure after its warmed up and driven about 20 miles. Haven't checked voltage at pump while driving. I had taken it to a seasoned tech of 20 years and he had replaced HPOP and 2 injectors and it does start better but problem is still there.
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I am installing a fuel pressure gauge into my 02 7.3 I went to the thread the sensor into the plug hole on the fuel filter housing and it wasn't threaded, turns out the sensor thread is slightly smaller and a different thread ... The directions say to install it into the filter housing or the lift pump ... So I'm assuming I have to go the lift pump direction of installing it but where the lift pump is or how to install the sensor into it while not throwing a code or causin problems ... A step by step and even pictures.
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So, I just had the fuel pump replaced on my '15 6.7 a month ago and it just died again. (next day edit: it didn't actually die, it showed all the same symptoms)
Same symptoms: whining sound, low fuel pressure warning, reduced power warning.
This time I'm 50 miles from home so I pulled off the road before it shut off. Interesting, I was in a hilly area and my low fuel warning came on too. We are waiting for a tow. I was considering trying to push on but don't want to get stuck in a dangerous spot on the highway. We're in a church parking lot.
So, last time this happened I was on flat road with about a half tank of fuel on a lunch break. I ran a mile after the warnings came on to feel out the issue and to see what would happen. I happened to be only about a mile away from my dealer so I drove that way. I got reduced power warning and then it cut power on me (limp mode). I made it to about 100 yards away before it cut off.
This time, I was in a hilly area at night on a windy two lane road with no shoulders in the woods. I was miles from civilization and was showing below a quarter tank of fuel. ~100 miles to EMPTY. I got the low fuel pressure warning first and then the reduced power mode before the whining noise started. I was climbing a hill on a curve at the time. I drove a quarter mile and then pulled off the road into a parking lot so I wouldn't be stuck on the shoulder. It didn't actually go into limp mode.
I let it sit a few minutes, talked it over with the wife and decided to call for a tow. After talking to the tow truck driver who said he would be an hour because he had to go find a bigger truck, I decided to see what I could do while I wait. I fired it back up and the fuel level dropped to below 1/8 and I was now showing 33 miles to EMPTY. I was parked on a hill with the back end up. I had backed the truck into a space to make it easier for the tow truck driver. I let it run a minute, checked for leaks and it seemed to run fine with no studdering or additional warning lights.
CEL was on but no new warnings. I put in my code reader and pulled the P0087. Just one code. I revved it a bit to see if there were any issues. It seemed fine so I decided to try my luck. I started driving towards home with the intention to stop at the first diesel station to fill up. Truck ran fine. After two minutes of driving gently, heart racing, my fuel level came back up and it now read 88 miles to EMPTY. I drove 11 miles to the nearest station and filled up. No issues. I shut it down. I fired it back up. Still no issues so with a full tank, I drove home the remaining 30 miles without issue.
Planning to take it in to the dealer Monday to get it checked. Could this be from an air pocked due to low fuel level and hilly terrain? Is my new pump dying already? Is there something else going on inside the tank or elsewhere?
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My high pressure power steering hose just blew at the "B" nut at the pump. Meaning, the fitting is still in the pump but the line is out. Do I need to replace the whole line or is there a retainer I can swap out?
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I just replaced my 3rd HP power steering line last night( 3rd in 300K, always blows the same point....fitting comes apart where it attaches to the pump.
I'll start, mine have gone about 100K plus or minus 10K, almost thinking about making it a 100K maintenance item.
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2003 f250 6.0 had a no start issue at first which ended up being bad connection/ chaffed wire at ficm.. ive replaced regulator with blue spring, new oil/fuel filter housing, new Motorcraft filters, and a orileys fuel pump.... guage i have reads 55psi at start up. While accelerating it obviously drops down, but it seems to goto 40 to 45psi then back to 50..then at times it goes back down while driving and stays around 40 45psi regardless if accelerating or coasting etc. Then after couple mins when i accelerate it will go back up?
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2003 F-350 - 7.3. With the key in the on position there is zero voltage to the fuel pump. Fuel pump fuse is good. I traced the red with black tracer wire from the pump up through the firewall and to the safety inertia switch. The switch has continuity so it's OK. Then from the safety switch I traced the green with yellow tracer wire to a fuse block plug connector. Then I checked continuity from that connector out to the #40 fuel pump fuse and it's open.
So I then i checked from the fuel pump fuse to all the back connections on the back of the fuse block and there was no continuity to any of them. So I removed the back cover off the fuse block to expose any issues. I found two board mounted relays. Now, from the fuse I get continuity to one of the relay connections. So did Ford hide the fuel pump relay and make it non replaceable? Also if this is the pump relay then what circuit energizes it? I need to make sure before I replace the fuse block.
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I have a 2003 F250 and dont have power at fuel pump, or fuse #30. I put power directly to fuel pump and it worked and truck fired right up.
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There was no power getting to the fuel pump on my 2002 Ford F250 73 diesel traced it back to the inertia switch no power in or out but I'm getting power at the fuel pump relay put the code scanner to the PCM and no communication....
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I was driving my truck then all sudden truck started losing power then slowly died. I restarted it, it was a lil shacky then died again. Iunscrewed the fuel filter and looked in the housing and there was lil fuel in bowl i turned the key to on position and bowl did not fill with fuel looked as if it were shooting some bubbles up(air) could it be outta of fuel???
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What I know the truck was running normal except if I stomped the gas pedal and let off it would not respond again until I shut off keys and restarted this was a month ago now the truck sounds like it has a lope tune.
When I hit the gas pedal it blows white smoke and if I press the gas while idling or driving it floods out I did the spray bottle test on manifolds the drivers side was plenty hot the passenger side is cold you literally can touch while it's running.
The truck sounds like it's only running on 4 cylinders it has gotten so bad I parked the truck. Also this truck always had poor mpg 8 to be exact city hwy and towing nothing changed the mpg at all it used to blow out wet soot that would fall down on the truck and anyone standing near it.
Mods unknown pcu program 4in straight pipe with 12in stack harpoon mod in tank
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I am a mechanic and tow operator running a late 99 f350 7.3 6 speed cab and chassis wrecker. This truck has had a hard life and has been neglected for quite some time, and now has become my baby/headache. Truck starts great, idles nice, and will run great for about 5 minutes until it starts billowing white smoke that smells like fuel and loses all power. If you continue to drive it it will die. Sounds like it's dropping cylinders and will barely idle. If you stop for 5 minutes or so and let it idle it will smooth back out and will run great again for another minute or two, then right back to stumbling.
Using torque app, hpop pressure looks good when it's running well. Peaks at 3k, IPR maintaining 30-40% max. As soon as it stumbles you can see the hpop drop to 5-600 and the IPR will climb to 65%. Let it idea bit and they go back to normal, and stay good until it stumbles again.
Ive changed the fuel pump, ICP,rebuilt FPR, change fuel filter, pulled and cleaned the fuel tank (metal tank, no delamination, looks perfect inside). Pickup screen looked good. Cleaned the IPR, cleaned the hpop reservoir, there was no screen inside. Checked voltage at fuel pump, 11.78 across the pump with it running. Pulled valve covers, no noticeable leaks around injectors. Injectors have less than 5k miles. Remans with 100% larger tips.
To me it seems like the lpop is not keeping up with the hpop under load, starving it until you idle and let it catch up. Could it still be bad injector orings? Bad lpop? Something I'm not thinking of?
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1st diesel was a 1997 F350 dually (White Lightning). Upgraded last year to a 2015 F350 (The Rocket Sled)- the kids named it hahaha. Had to take the 6.7 (9200 miles) into the shop... Last Sunday I took the truck out and about 5 minutes from home I got the low fuel pressure warning. Pulled over and tried to purge air out of fuel system- the low pressure pump was making a terrible racket. Turned around and limped home- reduced power came on soon after. Parked it until I could get to the dealership on Tues. Long story short- dropped it off at the dealer (low pressure pump still making noise/ no low fuel waning, just CEL light).
Called to check status today- dealer can't seem to duplicate problem. Service advisor said if mechanic can't find anything wrong, service manager was going to take it out and try to duplicate. The is the 2nd time I've got the low fuel pressure warming. The first time (around 4000mi. ) was in winter- I changed out fuel filters and it went away. I was towing the 5th wheel. Just had to vent-I have to get this figured out. I wouldn't thing the filter could get clogged within 5k miles. Have a camping trip scheduled next week!!
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I just had my first fuel filter change (about 9,000 miles). After the shop changed both fuel filters with factory Ford ones, a check engine light came on and a "low fuel pressure" warning, along with a "reduced engine power" warning. It also stalls a lot and takes a long time to restart.
Obviously, they didn't do it right. I suppose there is air in the lines or something didn't go back together correctly.
My '06 seemed to purge itself, but this truck obviously won't. It is not even driveable to get it back to the station, to see if they can correct the problem.
The thing is, I watched them do it, so if someone can ask me the right questions as far as what I saw, maybe I can lick the issue in the driveway myself.
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Changed the fuel filters. No issues in replacing.
Primed them by the book - key on 30 seconds 6 times
Now I have low pressure warning and reduced power.
All parts were FOMOCO...
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My truck gave me low fuel pressure and reduced pressure limp mode at 21,000 miles. The fuel and air filters were changed at 16,000. The dealer said all they found was the fuel filters (at 21,000) were what needed to be changed. Also, why does my truck hum??
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